This invention relates to a method and apparatus for removing closures from containers and, more particularly, to such a method and apparatus which is especially designed to remove screw caps from reusable beverage bottles prior to such bottles being cleaned and refilled.
The now common practice of providing beverages in returnable bottles which have metal screw caps, i.e., having metal closures which are threadably received on the bottle rather than being crimped thereon, have provided bottlers with a new problem. That is, it is not unusual for a consumer of a beverage to replace a screw cap on the bottle after the beverage is removed. When the bottle is of the returnable type, this means that the bottler will receive bottles to be refilled which are capped. The old cap must then be removed from the bottle by the bottler before the bottle can be cleaned and then refilled.
Various methods and mechanisms have been devised to automatically remove any screw caps on returned bottles being processed through a bottle filling assembly line. Most of such mechanisms are designed to unscrew the metal cap from the bottle. For example, some of such mechanisms rely on gripping tongs or the like to grasp the caps on passing bottles and unscrew the same therefrom. Because it is quite expensive to provide a sensing system for first determining whether or not a passing bottle has a cap on it, most of such mechanisms grip the threads on the neck of a bottle when a cap is not present. It will be recognized that it requires a highly complicated arrangement which will result in the gripping members not grasping the neck of a bottle with sufficient force to damage the threads, but which will grip any cap thereon with enough force to obtain the firm hold necessary for an unscrewing operation. Because of the difficulty in providing such a gripping head, most machines which rely on this principle are too complicated and sensitive to be reliable. Another approach which has been taken is to pierce the cap with a piercing tool which has a non-circular cross-section. Then when the tool is rotated, the edges of the tool in engagement with the periphery of the hole so pierced in the metal cap will, it is asserted, rotate the cap along with the tool. The bottling method and apparatus described in U.S. Pat. No. 3,775,829 is an example of such a method and apparatus. The difficulty with such an arrangement, though, is that it is not unusual for the cap to be so tightly secured on the container that rotation of the tool will enlarge the hole in the cap, rather than rotate such cap relative to the bottle. Thus, machines utilizing this approach have also not been well accepted.
In view of the problems with available decapping apparatuses, it is not unusual for bottlers to have caps on returned bottles actually removed manually. It will be appreciated, though, that because of the speed with which most modern bottling lines operate, i.e., cleaning and filling bottles at a rate of 300-600 bottles per minute, the amount of labor required for such an operation is prohibitively expensive.